No brake pedal diagnosis help

Popped a rear brake line. Pedal would go almost to floor before front brakes grabbed but made it home- about 3 miles.
Replaced corroded line along with several other suspect sections..
Couldn't get a gravity bleed to rear. Couldn't get a pressure bleed to rear.
Suspecting LSPV stuck?

Also noticed right front caliper piston stuck. Replaced both. Not getting gravity bleed to front either.
Tried hand vacuum pump to pull fluid from MC to front caliper- feels like pulling air.
Removed and bench bled MC. Reinstalled, literally no pedal- feels like pumping air.
Put plugs in two MC ports. Full pedal. Uncompressible.
MC must be OK?

Had buddy work the pedal while I observe. No fluid out of any connections. Fluid level never dropped. Sprayed soapy water at each connection. No obvious air.

Where do I go from here? Believe I two issues; stuck LSPV and inability to build pressure. Not necessarily related.
Advice?
Thanks.